Automobile lamp



I March24, 1936. R. w. JOHNSON 2,035,432

AUTOMOBILE LAMP Filed April 10, 1935 Sheets-Sheet l QSTANTIALLY NOT fl INVENTOR. v '1 5 ATTOR Y5 March 24, 1 936.

- 2,035,432 AUTOMOBILE LAMP Filed April 10, 1935 I 2 Sheets-Sheet 2 HGQIO IMAGE or (mow IMAGE or:

Patented Mar. 24, 1936 iJNlTE. STATES PATENT OFFICE AUTOMOBILE LAM-P Application April 10, 1935, Serial No. 15,588 6 Claims. (01. 240-4125) This specification and appended claims are of a lamp described originally in an application filed by me on January 9, 1933, under Serial Number 650,881, and constitutes a continuation in part of said identified application.

A further object of this description is to set forth certain details of the invention embodied in the lamp disclosed in the application identified above, which details are designed to carry my im proved lighting into effect.

A further object is to describe a lamp which functions upon a principle relying upon filament placement relatively to the lamp reflector, to obtain initial correctness of light placement and distribution in .a projected light pattern.

A further object is to produce a lamp possessing manifold characteristics for substantially transverse directional control of the beam without having to resort to movable mountings for the lamp, or of having any portion of the lamp movable relatively to another portion in order to obtain the desired results.

A further object is to produce a lamp having a manifold light source uniquely positioned to produce dual directional control of the light beam projected. therefrom, so that an inclinedly angular secondary beam projection may be obtained relatively to a primary substantially horizontal forwardly projected beam.

A further object is to produce a lamp which, by employing a multiple filament bulb, uniquely positioned as to the relationship between its filaments and its reflector, will project light patterns each having certain light placement and distribution factors in common, but controllable as to angular position of the respective patterns, as now will be described.

These and other objects are attained in the invention described in the following specification and illustrated in the accompanying drawings, in which;

Fig. 1 is a diagrammatic front elevation of a reflector and two lamp filaments of conventional V shape, showing the placement thereof relatively to axial vertical and horizontal planes of the associated reflector, within the scope of the invention originally set forth.

Fig. 2 is a diagrammatic view of reflector and filament relationship as shown in Fig. 1, upon a line such as 2-2 thereof, and positioned acutely to the vertical axial plane.

Fig. 3 is a view similar to Fig. 2, but showing the reflector-filament relationship as viewed upon a vertical line suohas3-'3 in Fig. 1.

Fig. 4 is a view illustrating diagrammatically the filament image as projected by a portion of the reflector represented by position 4 in Fig. 1.

Fig. 5 is a View illustrating diagrammatically the filament image as projected by a portion of the reflector represented by position 5 in Fig. 1. 5

Fig. 6 is a view illustrating diagrammatically the filament image as projected by a portion of the reflector represented by position 6 in Fig. 1.

Fig. '7 is a view illustrating diagrammatically the filament image as projected by a portion of the reflector represented by position I in Fig. 1.

Fig. 8 is a view illustrating diagrammatically the superposition of filament images shown in Figs. 4 and 6. a

Fig. 9 is a view illustrating diagrammatically the superposed relationship of filament images shown in Figs. 5 and '7.

Fig. 10 is a view illustrating diagrammatically the filament image as projectedby a portion of the reflector represented by position II] in Fig. 1.

Fig. 11 is a view illustrating diagrammatically the filament image as projected by a portion of the reflector represented by position H in Fig. 1.

Fig. 12 is a view illustrating diagrammatically the superposition of filament images shown in Figs, 5, '7, 10, and 11.

Fig. 13 is a view illustrating diagrammatically a commercial variation of the form of filament shown in Fig. 2, but. the functioning of which, in the light of the following disclosure of my invention is identical in substance and principle therewith.

Lamps having two filament bulb equipment are well known and are old in the art. Various positions have been given the lamp bulb in order that its filaments may occupy some definite location relatively to the focal center of the lamp reflector, but such positions always have been established upon or adjacent to a line or plane passing through the axis of the lamp reflectoro vertically. For example, a favorite position for the filaments of such a two filament bulb has beenv to locate the bulb with the filaments one above the other and the lower filament in the region of or on the focal center of the lamp reflector, the other filament occupying a position above the focal center of the reflector. It is well known that illumination of a focally positioned filament will produce a light beam which is projected in a substantially axial direction relatively '50 to the lamp, while illumination of a filament positioned above the focus will produce a beam which is downwardly inclined or substantially depressed relatively to the horizontal plane through the axis of the reflector. This phenomenon has been employed in divers ways for overcoming the objectionable glare which focally positioned filaments create when illuminated, all with the common function of aiming at the illumination of the roadway in major part with the same degree of illumination as is produced with a focally positioned filament.

The lamp I have chosen as illustrative of an embodiment of my invention is shown in Fig. 1 and employs one filament l4 located at an acute angle of not more than 20 degrees to the horizontal plane and to the upper side thereof as well as to the right of the vertical axial plane, as viewed from the front of the lamp, while the cooperating filament I5 is located to the left of the vertical axial plane, at an acute angle of not more than 20 degrees below the horizontal axial plane. In such positions as these the action of the filaments, upon illumination of each is as follows:

Filament l4 would cause the development of a beam projected from the reflector, with the region of high light intensity occupying a position slightly depressed and substantially to the right of the center line of the vehicle, as viewed by the driver, and as shown in full lines and represented by the superposed filament images in Fig. 12, with edge diffusion, not shown, occupying a' position which would serve to illuminate both the road surface and the ditch immediately in front of the vehicle and at a reasonable distance ahead of it.

If filament l5 were illuminated the light beam so projected would be one in which the region of high light intensity is elevated as shown in dotted lines in Fig. 12 and therefore is adapted to illuminate the road surface for a relatively great distance ahead of the vehicle, with edge diffusion, not shown, also elevated and therefore adapted to illuminate the road surface at a greater distance than does the diffused portion of the depressed beam. In addition to this elevated position. of the light beam, as shown by dotted lines in Fig. 12, it is obvious that its general direction will be to the left of the beam shown in full lines in Fig. 12.

If the lamp bulb is placed in the reflector so that its filaments occupy strictly horizontally opposite relationship, the effect would be to produce respective light beams which, when filament I4 is illuminated, would occupy a general position horizontally to the right of the center line of the vehicle, while illumination of the opposite filament l5 would produce a light beam directed horizontally toward the left of the center line of the vehicle, these beams possessing identical elevational characteristics.

It is obvious that the novelty incorporated in my disclosure consists in so placing the bulb in the lamp reflector that its filaments may occupy any position in which they lie within the limitations of the acute angle defined by the horizontal axial plane and a plane through the axis at an angle of not more than 20 degrees from said horizontal plane, and that further, the positions occupied by the filaments to each side of the vertical plane passing through the reflector axis, may be such that they lie at any desired distances from the vertical plane, in which the maximum distance will be substantially the distance between filaments, as when one filament occupies substantially the focal center and the other to one side of the focal center, and at any point within said 20 degree angle limitation.

Therefore, with this exposition of my invention and the limitations within which the principle will function, which limitations are defined by the vertical, horizontal and angular components described, with the understanding that manifold variations from these limiting factors may be made without departing from the spirit and scope of the invention, I will now set forth the principle underlying the provisions made above.

Bulbs of the type commonly known as automobile lamp bulbs, employ filaments of a form having legs or branches. One of these is the so called V filament shown in Fig. 2, and a modification thereof is the parallel leg filament shown in Fig. 13. I have chosen the better known of these two forms of filament as exemplary of the application of my invention, and therefore have shown Figs. 4 to 12 inclusive as being characteristic image projections of a V filament, although the parallel leg type of Fig. 13 would but differ in the parallelism of the legs as distinguished from the V association thereof as shown in Figs. 2, 4, 6, and 8 particularly.

In the projection of light from a reflector by the use of V or parallel bar filament bulbs, it is desirable to form beams of generally horizontal elongation and having the highest light concentration and intensity in the region of the center of the beam. This is accomplished effectively and with an additional valuable function of enabling the entire beam thus propagated to be displaced for variation of placement in either far-reaching, center-of-the-road placement, or in a right directional placement of substantially as far reaching characteristics but slightly depressed for relatively near ditch and roadside illumination purposes.

Were a bulb so placed that each of its filaments had its legs in a definite plane, the image projection from any point of the reflector at a right angle to the said plane would be an enlarged and exact shape of the filament, with the legs occupying their maximum spread. If the image projection from any point of the reflector at an angle to the first mentioned position were to be viewed as compared with the first mentioned image, it would be found that said image shows the legs closer together than the legs of the first projected image. The effect of viewing the image projected from points at increasing angles from the points normal to the plane of the filament, is to show gradually closer and closer placement of the filament legs until strictly superposed parallelism of the leg images is obtained. The effect in this transition is to observe a gradual elimination of the distance or space between legs, thereby overcoming the cenral dark spot between the filament image legs,

as well as creating a greater light concentration in the central part of the image. Now, inasmuch as a desirable light pattern image is preferably of materially greater horizontal than vertical dimension, placement of the filament legs in a substantially vertical plane will produce a horizontally positioned filament image from points of reflection normal to said vertical plane, while images from points at an angle not to exceed substantially 20 degrees from the normal or horizontal will show a gradual closing of the dark spot between filament image legs, thereby eliminating this dark spot in the propagated light pattern and at the same time maintaining substantial elongation and less but required breadth of light pattern with the light distribution therein tapering from relative weakness and diffusion from the edges toward a high light intensity in the substantially central portion thereof.

angle from the horizontal.

Inasmuch as the preference is to maintain horizontality of light pattern with said tapering increase in light intensity toward the center of the light pattern, I purposely place the lamp bulb in the reflector so that each of its filament planes occupies an angle not to exceed substantially 20 degrees from the vertical, which is equivalent to the placement of the bulb so that a line through both filament centers will not exceed a corresponding substantially 20 degree These respective angles are defined by the line 2-2 and the line containing points 4 and 6 in Fig. 1. If we assume a point 4, as shown in Fig. 1, to be that from which an image is propagated from either filament I4 or filament I5, a tipped'imagehaving full leg spread, as shown in Fig.4, isproduced. If a point 5, lying in the horizontal reflector axis, be selected as the source of propagation of the projected filament image, a horizontal image such as shown in Fig. 5, will be produced, but it will be found that the leg images now occupy a closed relationship in which no space or dark spot exists between filament leg images, thereby showing the creation of an elongated image of light having high central light intensity tapering off toward the edges. If a point 6 opposite to point 4 be selected, the filament image projected will be found to be as in Fig. 6, in which a reversal of Fig. 4 is obtained. Then, by selecting a point I, opposite to point 5, a horizontal filament image as in Fig. '7, will be found, reversely corresponding to Fig. 5. Likewise, a filament image propagated as from a point II], will produce a vertically disposed inverted filament image having a closed and pronounced leg overlapping somewhat as shown in Fig. 10, while a filament image propagated as from a point II, will produce a vertically disposed ncninverted filament image having closed and pronounced leg overlapping somewhat as shown in Fig. 11.

Obviously, were nothing but images of the type disclosed in Figs. 4 and 6 available for beam developement, superposition thereof would produce an effect somewhat as shown in Fig. 8, in which the center of the light pattern is quite free of light and presents the effect of a hole or blank space of darkness I6 surrounded by a substantially elliptic ring of light. However, by so tilting the bulb that its filaments occupy the acute angle limitations disclosed in Fig. 1, closed filament image projections of substantially horizontal placement of the character shown in Figs. 5 and '7 are produced, the superposition of which results in the compact horizontal beam of central high light intensity shown in Fig. 9. This very desirable result, amplified by the actual superposition of images of the intense closed type shown in Figs. 10 and 11, therefore creates an ideal basic beam condition upon which to work in the event any modifications thereof are desired by the use of prisms in the glass closure of the reflector, as is common practice in automotive head lamp design. or course, it is understood that images without number are produced from all parts of the reflector and that they all unite to produce a total of blended outlines which assume a generally elliptic shape having a horizontally elongated central area of high light intensity which tapers off into a. diffusion toward the edges, thereby resulting in a most desirable beam pattern upon which to work in bringing about modifications therein prismatically, as has been suggested.

The foregoing specific disclosure of the results use of filament l5. However, there is :the distinc- .tion between the respective filaments that filament I4, "being located preferably on or slightly above the horizontal axial plane and tothe right of the vertical axial plane of the reflector will produce images and a resultant beam located on or below the horizontal and to the right of the vertical as viewed by the driver, while filament I5, being located on or near the horizontal axial plane and on or closely adjacent to the focus of the reflector, as shown, will produce images and a resultant beam located on or about the horizontal and projected forwardly axially or closely adjacent theretoVTherefore, in view of this differentiation of filament placement it will be found that images therefrom will form respective beams slightly depressed from the horizontal and bearing right therefrom, with the other beam substantially horizontally projected and assuming elevation of substantially axial characteristics.

Having thus described my invention what I claim is 1. A lamp consisting of a reflector, and a two filament bulb mounted in the reflector and hav ing the filaments thereof located with one of the filaments to one side ofthe vertical axial plane of the reflector and above the horizontal axial plane and the other filament located to the opposite side of the vertical axial plane of the reflector and below the horizontal axial plane, said filaments being so positioned that a line joining their centers passes through the focus of the reflector and makes an angle of substantially twenty degrees with the horizontal axial plane of the reflector.

2. A lamp consisting of a reflector, and a two filament bulb mounted in the reflector and having the filaments thereof located with one of the filaments to one side of the vertical axial plane of the reflector and above the horizontal axial plane and the other filament located to the opposite side of the vertical axial plane of the reflector and below the horizontal axial plane, said filaments being so positioned that a line joining their centers passes through the focal axis of the reflector and makes an angle of substantially twenty degrees with the horizontal axial plane of the reflector.

3. A lamp consisting of a reflector, and a two filament bulb mounted in the reflector and having the filaments thereof located with one of the filaments to one side of the vertical axial plane of the reflector and above the horizontal axial plane and the other filament located to the opposite side of the vertical axial plane of the reflector and below the horizontal axial plane, said filaments being so positioned that a line joining their centers makes an angle of substantially twenty degrees with the horizontal axial plane of the reflector.

1. A light projector comprising a focalizing reflector and an electric bulb having its filament located in the region of the focus of the reflector,

the terminals of said filament being spaced apart said filament lying in a plane which makes an angle with the vertical and horizontal axial planes of the reflector and positioned so that a line joining the reflector focus and the center of the filament makes an angle of not more than twenty degrees with the axial horizontal plane, the magnitude of said angle being in direct proportion to the spacing of the terminals of the filament, so that the projected filament images will form an illuminated area with substantially no dark spaces therein.

5. A lamp consisting of a reflector, and a two filament bulb mounted in the reflector and having the filaments thereof located with one of the filaments at one side of the vertical axial plane of the reflector and above the horizontal axial plane and the other filament located at the opposite side of the vertical axial plane of the reflector and below the horizontal axial plane, said filaments being so positioned that their illuminating centers are in proximity to the focal point of the reflector and are located substantially further from said vertical axis than from said horizontal axis through said focal point.

6. A lamp consisting of a reflector having a concave portion located rearwardly of the focal point and a forward section located forwardly thereof,

and a two filament bulb mounted in said reflector, said filaments being separately energizable and having one of the filaments at one side of the vertical axial plane of the reflector and above the horizontal axial plane and the other filament located at the opopsite side of the vertical axial plane of the reflector and below the horizontal axial plane, both of said filaments lying in close proximity of the focal point, the illumination center of each filament being substantially nearer the horizontal axis of the reflector than the vertical axis whereby light from said concave portion of the reflector when said first mentioned filament is illuminated will be projected more to the right than downwardly and light from the forward portion of said reflector will be projected toward the opposite side of the beam.

ROY W. JOHNSON. 

